1. Field of the Invention
The present invention relates to a document or sheet feeder mechanism for a portable optical scanner.
2. Description of the Related Art
optical scanners are typically used to read the surface of a document having either textural and/or graphical information and to convert the information into digital signals which can be stored and processed by a digital computer. The scanned, digital information then can be used for a variety of applications. For example, scanned, digitized textural information may be stored in a database, wherein the user can search for desired documents by initiating a "word search," and scanned, digitized graphical information may be edited, and processed for pictorial print-out.
Optical scanning units are commercially available in a number of different sizes and configurations. Some of the relatively large, stationary units contain an integral document feeder mechanism which moves and scans the document(s) in a manner similar to that of a photocopying machine. Although effective in scanning documents, large stationary optical scanners typically occupy a relatively large amount of office space.
Other types of scanners include portable optical units which can be rolled across or passed over a document. These portable scanners are typically hand-held or motorized so that they can scan under their own power once placed on the document. The width of portable scanners typically is about 4" to 41/2" so that it can scan an 81/2" by 11" sheet of paper with two lengthwise passes. The user must move the portable, hand-held scanner in a lengthwise direction over the sheet two times to scan the entire contents of the document. Such a procedure is typically cumbersome, uneven, and results in errors in scanning due to the lack of stability of the hand. The portable, motorized scanner has wheels or rollers that move the scanner across the document once properly placed on the document and energized. However, the motorized scanner must be used on a relatively flat surface. Using a working surface with a grade may cause the scanner to drift from the document. The portable motorized scanner is an improvement over the portable, hand-held scanner in that it gives more steady movement, and thus more uniform results. However, when smaller document such as photographs or business cards are scanned, they are so small that both the hand-held and motorized portable scanners are unable to provide consistent and uniform results. Also, these types of portable scanners are awkward to use with small documents.